YAEIOUS MANtTEES. 325 



culture possible these must be increased or diminished 

 in given quantities. - With the barnyard manure it is 

 not possible to produce these changes, and it is most 

 natural to direct our attention to some other system of 

 manuring, where we can have the growth of the plant 

 more under our control ; and for this reason we cannot 

 endorse the opinion advanced by some, that organic 

 manures are the only ones that yield satisfactory re- 

 sults. The plant should find at its disposail, during 

 each period of its existence iall the principles it requires, 

 and for that reason the various elements should be 

 soluble at given timeis. Here we have ^n ai-gument in 

 favor of the mineral fertilizers over the barnyard ma- 

 nure. These facts for a long time were not fully 

 understood or appreciated, and even men like Liebig 

 committed errors, as he manufactured a fertilizer that 

 contained non-soluble elements, contending that if they 

 possessed the contrary qualities they would be soon 

 carried off by the rain, etc. In the case of barnyard 

 manure it is obliged to undergo various changes, pro- 

 duced by fermentation, before any portion can be ab- 

 sorbed by the root, and these^ as a general thing, are 

 in excess, which is mpst disastrous when beet culture 

 be considered, as these organic nitric elements^ as well 

 as the chlorides, etc., prevent the formation of the 

 sugar. The absorption of these seems to vary with the 

 humidity of the soil. 



Chemistry .has been able, through the exertions of 

 G-eorge Yille, as well as of other men of scientific fame, 



